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Mitosis and Cell Cycle
- Daughter Cells
- Produces 2 daughter nuclei
that have the same number
of chromosomes as the
parent cell and each other.
- There are different number of
chromosomes in Mitosis and Meiosis.
Meiosis conatins four daughter nuclei,
each with half the number of
chromosomes.
- Its different
because Mitosis
replicates the cell
whereas Meiosis
divides.
- Produces 2 daughter nuclei
that have the same number
of chromosomes as the
parent cell and each other.
- Stages of Mitosis
- 1. Prophase; in which the
chromosomes become visible and
nuclear envelope disappears.
- 2. Metaphase; the chromosomes
arrange themselves at the
centre of the cell. (Spindle)
- 3. Anaphase; each of the two threads
of a chromosome (chromatid) migrates
to an opposite pole.
- 4. Telophase; In which the
nuclear envelope reforms
- Interphase: Mitosis is always preceded by a period
during which the cell is not dividing. It is a period of
considerable cellular activity that includes the
replication of DNA.
- 1. Prophase; in which the
chromosomes become visible and
nuclear envelope disappears.
- Uses of Mitosis
- Growth; When two haploid cells fuse together to form a diploid cell
(contains all the information needed to form a new organism). If the
new organism is to resemble its parents all the cells that grow from
the original must possess the same set of genetic information.
- Differentiation; These cells change to give groups of specialised
cells e.g epithelium in animals or xylem in plants. These different cell
types each divide by mitosis to give tissues made up to identical
cells which perform a paticular function. This is essential as the
tissue can only function efficiently if all its cells have the same
structure and perform the same function
- Repair; If cells die or are damaged it is important
that the new cells have identical stucture and
function. If they are not exact copies the tissue
would not function effectively as before. Therefore
Mitosis helps replace damaged or dead cells.
- Growth; When two haploid cells fuse together to form a diploid cell
(contains all the information needed to form a new organism). If the
new organism is to resemble its parents all the cells that grow from
the original must possess the same set of genetic information.
- Cell Cycle
- 1. Interphase; which occupies most of the cell cycle and is
sometimes known as the resting phase because no
division takes place;
- a. First Growth (G1) when the proteins
from which cell organelles are
synthesised are produced
- b. Synthesis (S)
when DNA is
replicated
- c. Second Growth (G2) When organelles
grow and divide and energy stores are
increased
- a. First Growth (G1) when the proteins
from which cell organelles are
synthesised are produced
- 2. Nuclear division
when the nucleus
divides either into 2
(mitosis) or four
(meiosis)
- The length of 1 cell cycle depends
on the cell. Typically a mammlian
cell takes about 24 hours to
complete of which 90% is
interphase.
- Cancer; caused by a growth disorder of cells. It is a result of
damage to the genes that regulate mitosis and the cell cycle.This
leads to uncontrolled growth of cells. As a result a tumour
develops and constantly expands in size.
- 1. Interphase; which occupies most of the cell cycle and is
sometimes known as the resting phase because no
division takes place;
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